Drilling mud has been utilized in hydrocarbon reservoirs for many years. The mud is used to establish a proper rate of penetration of the drill bit into the hole. Many variables, such as the desired hole depth, are considered when determining the necessary properties of the mud, and what materials are required to achieve the required consistency. The mud may include minerals called barite or hematite, both of which are very dense. Other components in the mud may include a clay mineral that is intended to seal and lubricate the wall of the hole and create a specific rheology in the drilling mud.
As the hole is drilled, drilling mud is constantly pumped down to the drill bit in order to clean the cuttings away from the bit. The mud then returns to the surface, carrying the drill cuttings with it. The spent drilling mud comprises a variety of materials, such as sand, clay, barite, hematite and/or drill cuttings, for example. The barite and hematite are added to the mud in order to increase the fluid density, and these minerals are very expensive. As such, there are a variety of conventional techniques to recover these minerals with the drilling fluid for re-use, while separating the drill cuttings for discard.
One of the conventional separation techniques utilizes a screen, which separates the particles in the mud based on size. However, the disadvantage to such a method occurs when the sizes of the cuttings are substantially the same size as the barite or hematite. As such, the screen is ineffective in isolating the barite or hematite. A second common separation technique is the centrifuge. This machine uses high acceleration forces in order to pin dense particles to the wall of a spinning chamber where they are removed and recovered. However, the disadvantage to this method is that coarser undesirable drill cuttings also become pinned to the wall together with the dense minerals. Therefore they are also recovered, even though it is more desirable to discard these particles.
In view of the foregoing, there is a need in the art for a separator to overcome or alleviate the before mentioned shortcomings of the prior art.